It has often been noticed that discarded chewing gum adheres to unwanted objects such as shoe soles, clothing , chair bottoms, carpeting, floors, etc. It would be desirable to be able to remove such gum from these areas without having to resort to organic solvents, since the solvent may not only dissolve the gum, but may also harm the object to which the gum is adhering. Thus, it is desirable to produce a chewing gum base which has the following characteristics:
1. excellent mouth feel, with no trace of slipperiness or sliminess, PA1 2. dispersability in cold water so that it is easily removable from unwanted areas without necessitating the use of organic solvents, PA1 3. good chewing quality so that it promotes the desire to chew. PA1 a. Less acetic anhydride is required for a lower degree of substitution. PA1 b. A large portion of free toluene separates from the low acetyl gum latex, and may be separated by decantation, rather than by distillation from the gum. PA1 c. A highly purified gum may be recovered by dissolving the crude gum in cold water, and then re-precipitating by heating.
Accordingly, one of the principal objects of the present invention is to provide a chewing gum which is readily dispersible in cold water so that it is easily removable from unwanted areas by means of cold water washing, while at the same time, maintaining an excellent mouth feel, good cohesion.sup.1 and stretch.sup.2, and remaining insoluble when chewed. FNT .sup.1 Cohesion is the opposition offered to the teeth at the end of the bite as compared to the start. This property promotes the desire to chew. FNT .sup.2 Stretch is that property which enables a sample to be pulled out in a ribbon to some length.
A further object is to provide a chewing gum having the foregoing properties which can be produced economically.
In U.S. Pat. No. 3,666,492 issued May 20, 1972 to Teng and Rha there is disclosed a fatty acid ester of starch, as a chewing gum base. The invention of U.S. Pat. No. 3,666,492 involves a saturated fatty acid having from 8 to 14 carbon atoms (specifically starch laurate), and a degree of substitution of above 2.
In U.S. Pat. No. 3,883,666 issued May 13, 1975 to Teng and Stubits there is disclosed a hydroxypropyl starch acetate, as a chewing gum base. The invention of U.S. Pat. No. 3,883,666 involves a hydroxypropyl starch acetate having a degree of molecular substitution of hydroxypropyl radicals of about 3 to about 6 and a degree of substitution of acetyl groups of about 1.0 to about 2.5. The gum base of U.S. Pat. No. 3,883,666 is entirely insoluble in both hot and cold water.
We have discovered a hydroxypropyl starch acetate with a degree of substitution of hydroxypropyl radicals of about 3 to about 6 and a degree of substitution of acetyl groups of about 0.5 to about 0.9. This hydroxypropyl starch acetate is suitable as a chewing gum base as it is an elastic, cohesive solid mass at temperatures of 35.degree. C. and higher. At these temperatures it possesses excellent chewing quality and good mouth feel. In addition to the foregoing properties, this gum disperses readily in cold water (20.degree. C. or below) to give a milky, or translucent dispersion.
This gum base has the following advantages over conventional gum bases:
1. Chewing gum made essentially of this gum base may be removed from unwanted places, e.g., children's hair, clothing, furniture, by simply washing with cold water, rather than by dissolving in organic solvents or by employing destructive mechanical means.
2. Compared to the gum made in accordance with U.S. Pat. No. 3,883,666 the cost is lower for the following reasons: